I've set my profile picture only available for Friends.
However it's still visible for the public.
Non-authenticated users can see the profile thumbnail and authenticated (non-friends) can still click and see the full picture.
I've already activated option 'Limit Past Posts' in Privacy, but it didn't solve the problem.
Best Answer
You can't!
Facebook won't allow you to hide your profile picture and cover photo (these will be always public, no matter what are you settings). The workaround is to simply change/blur the profile picture, create a fake profile (which isn't allowed) or deactivating your account for some period of time.
On Facebook Help Centre we can read:
See: